03092nas a2200193   4500008004100000245012700041210006900168260004300237300001000280490001400290520242700304653002202731653001802753653003002771653002302801100001802824700001902842856003702861       2012                        eng d00aMechanisms driving woody encroachment in the tallgrass prairie: an analysis of fire behavior and physiological integration0 aMechanisms driving woody encroachment in the tallgrass prairie a  aManhattan, KSbKansas State University  a1 -720 vMS Thesis3 a<p>Woody encroachment has altered the vegetative structure of grasslands worldwide and represents a potentially irreversible shift in grassland dynamics and biodiversity. Clonal woody species appear to be one of the greatest contributors to the shift from graminoid to woody dominance in the tallgrass prairie. Part of the high success rate of clonal species may be attributed to an ability to circumvent recruitment filters through the integration of environmental heterogeneity and acropetal translocation of resources from mother to daughter ramets. The clonal shrub Cornus drummondii persists in a tension zone of the graminoid-dominated tallgrass prairie, where the dominance structure is primarily maintained through the direct and indirect effects of fire. The competitive displacement of native herbaceous vegetation associated with the establishment and expansion of C. drummondii causes a major alteration in the fuel dynamics responsible for the propagation and sustainment of fire, potentially contributing to biofeedback mechanisms that facilitate shrub expansion. The goal of this research was to quantify fire behavior parameters (temperature, intensity, rate of spread, and heat flux) in relation to C. drummondii invasions and to test physiological integration as a mechanism driving encroachment, using manipulation experiments at the Konza Prairie Biological Station. We observed a significant decrease in fireline intensity associated with the encroachment of C. drummondii, which was amplified by the effects of stem density and shrub island area. This alteration in fire behavior also led to reduced heat flux at stems within shrub islands, reducing the likelihood of tissue necrosis and top-kill. With additional fuel, temperatures and fire intensities were higher, similar to open grasslands. In severing rhizomes, and effectively severing the integration of clonal ramets, we observed a higher risk of mortality of daughter ramets. These rhizome severed ramets were more water stressed, had lower photosynthetic rates, and lower woody and foliar biomass production. These results indicate that C. drummondii significantly alters fire behavior, releasing ramets from the fire trap of successive top-killing, while the integration of intraclonal ramets allows daughter ramets to survive mid-summer drought and increases the likelihood of successful establishment and further clonal reproduction.</p>10aCornus drummondii10aFire behavior10aPhysiological integration10awoody encroachment1 aKillian, P.D.1 aBriggs, J., M.  uhttp://hdl.handle.net/2097/1419702744nas a2200229   4500008004100000245010100041210006900142300001500211490000700226520198700233653000702220653000702227653002202234653000902256653001002265653002202275653003202297653002002329100001902349700002002368856012602388       2003                        eng d00aC3 shrub expansion in a C4 grassland: positive post-fire responses in resources and shoot growth0 aC3 shrub expansion in a C4 grassland positive postfire responses  a1496 -15010 v903 aChanges in land management and reductions in fire frequency have enabled woody species to increase in grasslands worldwide. Nevertheless, fire is rarely eliminated from grasslands, and for shrubs to survive, they must be able cope with fire and replace aboveground structures. Because new shoots may have more available solar radiation, greater root : shoot ratios, and thus more resources available belowground after fire compared to undisturbed shrub communities, we hypothesized that carbon, nutrient, and water relations may be enhanced in stems compared to those in an undisturbed grassland. However, this same post-fire resource pulse stimulates the grasses and may intensify competitive interactions between shrubs and grasses. To test these predictions, we measured seasonal patterns in net photosynthesis (A), predawn xylem pressure potentials (XPP), leaf nitrogen (N) content, and productivity of Cornus drummondii shoots from shrub patches (islands) of different sizes in mesic grasslands burned annually, burned infrequently, and protected from fire. Seasonal average A was 20% higher (P = 0.016) in burned than in unburned shrubs, regardless of island size. Shrubs in burned sites also produced shoots with higher leaf N than unburned shrubs, and N content was higher in leaves from small islands compared to large islands (P < 0.0001). Burning caused a decrease in late summer predawn XPP in small islands (−3.1 MPa), whereas burned large islands did not differ from unburned shrubs. Post-fire productivity of new shoots was significantly greater compared to shoots in unburned sites. These results indicate that a transient period of high resource availability after fire allows for increased growth and rapid recovery of grassland shrubs. Thus, although fire has a negative effect on aboveground biomass of shrubs, the post-fire increases in resource availability, which enhance growth in the dominant grasses, are also important for recovery of woody species.10aC310aC410aCornus drummondii10afire10ashrub10atallgrass prairie10atransient maxima hypothesis10awoody expansion1 aMcCarron, J.K.1 aKnapp, Alan, K.  uhttp://lter.konza.ksu.edu/content/c3-shrub-expansion-c4-grassland-positive-post-fire-responses-resources-and-shoot-growth02811nas a2200193   4500008004100000245010200041210006900143300001300212490000700225520210600232653002202338653002302360653002202383653002302405653002602428100001502454700002002469856012802489       2003                        eng d00aConsequences of shrub expansion in mesic grassland:  resource alterations and graminoid responses0 aConsequences of shrub expansion in mesic grassland resource alte  a487 -4960 v143 aIn the mesic grasslands of the central United States, the shrub Cornus drummondii has undergone widespread expansion in the absence of recurrent fire. We quantified alterations in light, water and N caused by C. drummondii expansion in tall-grass prairie and assessed the hypothesis that these alterations are consistent with models of resource enrichment by woody plants. Responses in graminoid species, particularly the dominant C4 grass Andropogon gerardii, were concurrently evaluated. We also removed established shrub islands to quantify their legacy effect on resource availability and assess the capability of this grassland to recover in sites formerly dominated by woody plants. The primary effect of shrub expansion on resource availability was an 87% reduction in light available to the herbaceous understorey. This reduced C uptake and N use efficiency in A. gerardii and lowered graminoid cover and ANPP at the grass-shrub ecotone relative to undisturbed grassland. Shrub removal created a pulse in light and N availability, eliciting high C gain in A. gerardii in the first year after removal. By year two, light and N availability within shrub removal areas returned to levels typical of grassland, as had graminoid cover and ANPP were similar to those in open grassland. Recovery within central areas of shrub removal sites lagged behind that at the former grass-shrub ecotone. These results indicate that the apparent alternative stable state of C. drummondii dominance in tall-grass prairie is biotically maintained and driven by reductions in light, rather than resource enrichment. Within areas of shrub removal, the legacy effect of C. drummondii dominance is manifest primarily through the loss of rhizomes of the dominant grasses, rather than any long-term changes in resource availability. C. drummondii removal facilitates grassland recovery, but the effort required to initiate this transition is a significant cost of woody plant expansion in mesic grasslands. Prevention of woody plant expansion in remnant tall-grass prairies is, therefore, a preferred management option.10aCornus drummondii10aGrassland recovery10aland cover change10aTall-grass prairie10aWoody plant expansion1 aLett, M.S.1 aKnapp, Alan, K.  uhttp://lter.konza.ksu.edu/content/consequences-shrub-expansion-mesic-grassland-resource-alterations-and-graminoid-responses01911nas a2200241   4500008004100000245013300041210006900174300001300243490000700256520105200263653002701315653002701342653001201369653002201381653001801403653002001421653002101441653002201462653002501484100001501509700001601524856012901540       1995                        eng d00aAntimicrobial activity of dogwood fruits (Cornus drummondii) from winter food caches of the eastern woodrat (Neotoma floridana )0 aAntimicrobial activity of dogwood fruits Cornus drummondii from   a419 -4250 v213 aPost-harvest loss of resources to microbial competitors affects a number of species of animals, and many of them have evolved behaviors that reduce the likelihood of such loss. We previously described the inhibition ofBacillus psychrophilus by dogwood fruits (Cornus drummondii), which can comprise a significant portion of the winter food cache of the eastern woodrat (Neotoma floridana). The present study is a further investigation of the ability of dogwood fruits to inhibit growth ofB. psychrophilus. Additionally, we tested the antimicrobial activity of dogwood fruits onEscherichia coli andStaphlococcus aureus. Results of our study indicate that fresh fruits inhibit the growth ofB. psychrophilus andS. aureus but notE. coli. However, fruits taken from woodrat dens after four and six months storage inhibited growth of all three species of bacteria. Further, the strength of inhibition increased over the test period. We suggest the presence of an inhibitor allows woodrats to compete effectively for a valuable and limited food resource.10aantimicrobial activity10aBacillus psychrophilus10acaching10aCornus drummondii10adogwood fruit10aeastern woodrat10aEscherichia coli10aNeotoma floridana10aStaphlococcus aureus1 aPost, D.M.1 aUrban, J.E.  uhttp://lter.konza.ksu.edu/content/antimicrobial-activity-dogwood-fruits-cornus-drummondii-winter-food-caches-eastern-woodrat